In case that a smart phone application, in the following called “application”, connects to a portal/server entity of a network operator or service provider via a mobile communication network, the mobile communication network knows the IP address and thus is able to identify the subscriber (that could, of course, also be a M2M device (Machine to Machine communication device) or a MTC (Machine Type Communication) device) by mapping the current IP address to the MSISDN (Mobile Subscriber ISDN (Integrated Services Digital Network) Number).
However if the connection to a server entity/portal is done while the communication device (or the user equipment or the M2M/MTC device) is connected, e.g., via a WLAN, the network operator or service provider (i.e. the server entity or the portal) does not know (at least not for sure) the identity of the subscriber/device, especially not the MSISDN number.
For operator based billing services or M2M services, the MSISDN of a customer is often used as identification attribute. Therefore it is important that the correct MSISDN of a subscriber is known to the service provider and used for billing or for reaching the M2M device.
There are several conventional methods available to authenticate and/or identify the user, e.g. by using OTP (one time PIN, which is sent e.g. via SMS to the mobile with the MSISDN provided by the customer) or via prior registration and log in with username and password. However, these conventional authentication mechanisms are cumbersome for the user.